This invention generally relates to the fuel processing art and more specifically concerns a method and apparatus using principles of pyrolysis by which fuel gases without tars are produced from organic materials.
Large amounts of organic material are burned or otherwise disposed of as waste each year. This is particularly true for certain cellulose products such as straw and the slash residue of logging operations. It is typical present practice to burn such material, since it is usually uneconomical to dispose of it in any other way.
There have been previous attempts to beneficially use such material, but these attempts have heretofore been shown to be impractical. In one prior attempt to use such material for a beneficial purpose, carbon monoxide is reacted with organic material at high temperatures and very high pressures to form a liquid fuel similar to crude oil. However, this process is impractical because of the expense of transportation of the organic material, the high cost of the equipment to implement the process, and the follow-on costs necessary to refine the crude oil.
In another known apparatus, referred to generally as a gasogen, a combustible fuel mixture, useful as a fuel for internal combustion engines, is produced by burning organic material in a limited-air environment. In the gasogen, volatile gases, i.e. carbon monoxide and hydrogen, are driven off from the organic material. These gases can be used directly as a motor fuel. However, substantial amounts of tars and other nonusable byproducts are produced when the material is burned. These tars and other byproducts must be filtered from the gases before the gases can be used. In addition, the air used in the combustion process also passes through the carburetor of the engine using the fuel, which has been found to detract considerably from the power output of the apparatus.
A technique known as pyrolysis, which involves the heating of materials in the absence of air to a sufficient degree to result in a chemical reaction which produces carbon monoxide, water vapor and hydrogen volatiles, has also been used to a limited extent in this area. The pyrolysis process, however, also produces undesirable tar byproducts, much the same as the gasogen.
In view of the significant amounts of waste organic material created each year, which must be disposed of in some way, there remains a significant need for a process and apparatus which can economically use such material to produce a useful product.
Accordingly, a general object of the present invention is to provide an apparatus and a method for producing a useful product, such as a fuel, from waste organic material.
It is another object of the present invention to provide such an apparatus and method which does not in addition produce tar or other undesirable byproducts.
It is a further object of the present invention to provide such an apparatus which may be conveniently transported to, and used at, the site of the organic material.
It is yet another object of the present invention to provide such a process which may be implemented on a large scale in a stationary plant.